Fault Diagnosis And Fault-tolerant Control In Direct-Drive PMSG Wind Turbine Converters

To realize the world energy transformation and sustainable development,the pace of global “carbon reduction” continues to accelerate.Due to the abundant reserves and mature technology,wind energy has become the most potential renewable energy for large-scale development,which has injected strong green power into the realization of “carbon neutrality”.With the release of the 14 th Five-Year Plan,the prospect of wind power industry is prosperous,and it is an inevitable trend to accelerate the development of wind power.At the same time,as the key equipment and vulnerable link of direct-drive permanent magnet wind power system,it is more important to improve converters’ reliability and availability.Accordingly,this paper cites IGBT open-circuit faults of converters in a 2MW direct-drive PMSG wind turbine as the study object,the fault diagnosis and fault-tolerant control strategy for multiple open-circuit faults of the converters are studied,the main research work is described as follows:Firstly,construction and modification of numerical model of direct-drive PMSG wind power system.Based on MATLAB / Simulink platform,the numerical model is built,and the parameters of the model are modified by using SCADA data of wind farm to improve the model performance,it can provide the design and simulation of fault diagnosis and fault-tolerant control method with a basis.Secondly,theoretical analysis of open-circuit fault characteristics of wind power converter.The open-circuit fault is classified into five fault types,and the influence of open-circuit fault on the system operation characteristics is analyzed according to the voltage variation characteristics in the converter circuit equation.Combined with the simulation,the waveform distortion of the phase current,THD and the variation of other operating parameters of the converter system after the open circuit fault are obtained,which verifies the correctness of the theoretical analysis and provides reference for further research.It provides a theoretical basis for further study of open-circuit fault diagnosis and fault-tolerant control strategy.Thirdly,design of open-circuit fault diagnosis strategy for wind power converter.The phase current signal is selected as the diagnosis basis,and the open-circuit fault diagnosis method based on exponential transformation and amplitude reconstruction is proposed,which is divided into two tasks: the first one is the fault detection and the second one is the fault localization.The detection method is based on the relative current residuals after exponential transformation,amplitude reconstruction and on an adaptive threshold,and the localization method is based on the average values of fault phase currents.For validating this,robustness test and multiple open-circuit faults diagnosis are presented in a 2-MW direct-driven PMSG wind turbine system,and compared with the existing fault diagnosis methods.The results validate the reliability and effectiveness of the proposed method,which provides a research basis for the design of fault-tolerant control technology.Finally,a fault-tolerant control method is proposed based on SVPWM reference voltage vector reconstruction,via analyzing the influence of different fault types on SVPWM space voltage vector.The fault reference voltage vector can be reconstructed by reselecting the available basic space vector and redistributing the action time of each vector.Combined with the fault diagnosis system,a complete open-circuit fault diagnosis and fault-tolerant control model of wind power converter is constructed in the MATLAB/Simulink environment.The simulation results verify the effectiveness of the proposed fault-tolerant control method,which can effectively reduce the degree of current distortion and the fluctuation of DC-Link voltage.